1. Field of the Invention
The present invention relates to an aspirating device for removing undesirable secretions from a mammalian body and more particularly concerns an aspirating device for use in suctioning undesirable secretions from the trachea of a patient.
2. Description of Related Information
Various forms of respiratory therapy require the use of a ventilator which is a device which provides for the movement of gases into and out of the pulmonary system. Usually a ventilator is used in conjunction with some form of arterial airway or tube which is inserted into the patient's trachea through the mouth (endotracheal tube) or into the patient's trachea through an incision in the patient's neck (tracheostomy tube). The tracheostomy procedure is sometimes preferred because it bypasses and therefore avoids complication with portions of the upper airway.
Artificial airways are established for adequately supporting ventilation for an extended period of time. The artificial airway also prevents a potential danger to the patient by diminishing the patient's ability to cough and to voluntarily remove undesirable secretions from the trachea. Accordingly, the removal of the secretions from a patient having a temporary artificial airway, for example, during therapy involving a ventilator, is affected by aspiration or suctioning. Patients with a substantial amount of secretions require frequent aspiration or suctioning to remove secretions from the trachea.
A known and available suctioning device is a suction catheter as described in U.S. Pat. No. 3,319,628 to Halligan. The suction catheter, as taught by Halligan, is connected to a source of vacuum and is inserted through the artificial airway and into the trachea of the patient wherein the suction forces draw secretions into the catheter and out of the trachea and the artificial airway. Halligan teaches an improved catheter having means for manual regulation of the vacuum forces. In particular, Halligan teaches a suction catheter comprising a flexible catheter having an opening at its distal end and a rigid regulator at its proximal end. The regulator includes a bore which is aligned with the lumen of the catheter and a second bore which is perpendicular to the fluid path of the catheter in the first bore. A finger engaging piece is associated with the regulator and includes a concave surface adapted to receive the finger of the user for occluding the secondary bore. The secondary bore acts as a bleed so that when it is not occluded, outside air enters the bore in the vacuum line and reduces the vacuum forces at the distal tip of the catheter to substantially zero while occluding the secondary bore with the finger terminates all bleed air and maximizes the vacuum forces at the tip of the catheter and partial occlusion will tend to provide vacuum forces between the two extremes. The catheter taught by Halligan provides an effective device for suctioning the trachea and the other body passageways. These suction catheters are simple in structure, maneuverable, easy to regulate with respect to suction forces and disposable. The disposability is believed to be a desirable feature because bacteria encountered in the patient's trachea is deposited on the exterior of the catheter and under certain circumstances will continue to grow and multiply. Also, after removal of the catheter from the patient, other airborne bacteria may contact the catheter and grow on its surface. Accordingly, reusing such an instrument is believed to be hazardous to the patient because it could introduce bacteria into the respiratory system. A similarly structured suction and oxygenation catheter is taught by Gandi et al. in U.S. Pat. No. 4,300,550.
Radford, in U.S. Pat. No. 3,991,762 teaches a reusable aspirating device for use with the patient ventilation apparatus. In one embodiment, Radford teaches an aspirating device consisting of a catheter tube and a protective housing. The protective housing includes a patient coupling element slidably positioned so as to surround the catheter tube nearest that end thereof suitable for insertion into the trachea and a vacuum coupling element mounted adjacent to the end of the catheter remote from the end adapted to be inserted into the trachea. A protective envelope extending between the patient coupling element and the vacuum coupling element is formed of a flexible plastic material which distorts and compresses when the vacuum coupling element and the patient coupling element are moved relatively toward one another. The patient coupling element also includes a seal surrounding the catheter tube, and adapted to help prevent fluid secretions located on the exterior surface of the catheter from being withdrawn into the envelope, and an irrigation port suitable for connection to an irrigation source and in communication with the external surface of the catheter tube. Radford teaches that the aspiration device should remain connected to the ventilation apparatus via the patient coupling element and that the same catheter can be reused many times by a single patient. Although the Radford aspirating device appears to be more expensive to manufacture it may be an improvement, with respect to cost, if several aspirating procedures can be performed with the same device which remains continuously connected to the ventilator during the patient therapy. Also, the apparatus taught by Radford, offers the advantage of being usable without disconnecting the ventilator so that it is not necessary to follow the procedure of pre-oxygenating the patient before using the suction catheter and a subsequent reoxygenating step after use of the suction catheter. In addition, the respiratory therapist using the device of Radford is not under the time pressure to perform the suctioning procedure in a minimal amount of time while the ventilator is disconnected.
An aspirating device substantially similar to the device of Radford is taught in U.S. Pat. No. 3,902,500 to Dryden. Dryden's aspirating device does not include a seal surrounding the catheter tube and an irrigation port in the patient coupling element.
U.S. Pat. Nos. 4,569,344 and 4,638,539 to Palmer teach what appear to be improvements to the Radford device regarding specific structures for the patient coupling element and a vacuum coupling element including a lockable vacuum control valve in the vacuum coupling element.
U.S. Pat. No. 4,691,702 to Chantzis teaches an aspirating device which in one embodiment includes a patient housing, a flexible catheter, a vacuum coupling housing at the proximal end of the catheter and a flexible sleeve surrounding a portion of the catheter. Unlike the aspirating devices of Radford, Dryden and Palmer, the aspirating device of Chantzis teaches a flexible sleeve which is contained within the patient housing and is not connected to the vacuum coupling housing so that any portion of the catheter or the sleeve which contacts secretions in the trachea of the patient cannot pass through the proximal end of the patient coupling housing thereby confining these surfaces to a specific protected area within the patient coupling housing.
Although the devices taught by Radford, Dryden and Palmer may provide some advantages over the prior art suction catheters, they still have disadvantages. Most notably, the vacuum connection housing, which usually contains a valve to control the vacuum forces, is a substantial distance from the patient coupling element and the patient's throat area. Since the catheter and the protective envelope are flexible the vacuum housing is free to move around and possibly become entangled with the patient bed frame or other adjacent apparatus so that further movement with respect to the patient can disconnect the elements of the catheter assembly and/or possibly cause patient trauma by applying forces to the endotracheal tube or tracheostomy tube. Also, inadvertent action by the patient or other party on the remote vacuum control valve may cause initiation of vacuum forces when they are not desired and may be detrimental to the patient. To avoid this problem Palmer, in U.S. Pat. No. 4,569,344, teaches a valve that may be manually locked in a closed position to prohibit inadvertent actuation of the valve. Also, this type of aspirating device requires the movement of the entire mass of the vacuum coupling element and associated valve whenever the catheter is moved along the trachea of the patient. In addition, when a shielded catheter is connected to a patient ventilating unit it is desirable not to have flow of the ventilation gases into the aspirating device which would be tantamount to a leak lowering the efficiency of the ventilation device. The teachings of the prior art do not appear to recognize this as a serious problem, however, the seal taught by Radford to remove secretions from the outside of the catheter would also be helpful in reducing the effect of the ventilator on the envelope so that the ventilator pressures cause the patient's lungs to expand and contract and not the catheter envelope.
Catheters and catheter assemblies for use in suctioning of the trachea and other passages in the patient's body, for use alone or with a ventilator, both disposable and reusable, have been addressed by the prior art. However, there is still a need for a simple, straight-forward, reliable, easily fabricated reusable aspirating device having an improved structure fixing the position of the vacuum coupling element and valve to minimize the potential for inadvertent actuation or inadvertent assembly and to allow movement of the catheter into and out of the patient's trachea without moving valves and other structural elements. It is also desirable to have a more effective seal between the ventilator and the aspirating device so that, while not in use, the ventilator does not force gases into the catheter sheath.